import React from 'react';
import scss from "../../../assets/styles/map.module.scss";
/**
 * 
 * @param el 
 * @param event 
 * @param handler 
 * @returns 
 * 
 * 添加拖动事件
 */
const addEvent = (el: any, event: any, handler: any) => {
    if (!el) return;
    if (el.attachEvent) {
        el.attachEvent('on' + event, handler);
    } else if (el.addEventListener) {
        el.addEventListener(event, handler, false);
    } else {
        el['on' + event] = handler;
    }
};
/**
 * 
 * @param el 
 * @param event 
 * @param handler 
 * @returns 
 * 移除拖动事件
 */
const removeEvent = (el: any, event: any, handler: any) => {
    if (!el) return;
    if (el.detachEvent) {
        el.detachEvent('on' + event, handler);
    } else if (el.removeEventListener) {
        el.removeEventListener(event, handler, false);
    } else {
        el['on' + event] = null;
    }
};
interface State {
    needX: number;
    needY: number;
}
interface Props {
    style: any
}
/*拖拽组件*/
class Drag extends React.Component<Props, State> {
    disX: any;
    disY: any;
    constructor(props: any) {
        super(props);
        this.state = {
            /*定义两个值用来存放当前元素的left和top值*/
            needX: 90,
            needY: 150,
        }
        /*定义两个值用来存放鼠标按下的地方距离元素上侧和左侧边界的值*/
        this.disX = 0;
        this.disY = 0;
    }
    /*定义鼠标下落事件*/
    fnDown = (e: any) => {
        /*事件兼容*/
        const event = e || window.event;
        /*获取鼠标按下的地方距离元素左侧和上侧的距离*/
        this.disX = event.clientX - this.state.needX;
        this.disY = event.clientY - this.state.needY;
        // /*定义鼠标移动事件*/
        addEvent(document, 'mousemove', this.fnMove);
        // /*定义鼠标抬起事件*/
        addEvent(document, 'mouseup', this.fnUp);
    }
    /*定义鼠标移动事件*/
    fnMove = (e: any) => {
        /*事件兼容*/
        const event = e || window.event;

        let x = event.clientX - this.disX;
        let y = event.clientY - this.disY;
        if (x > 1574) x = 1574;
        if (y > 535) y = 535;
        this.setState({
            needX: x < 0 ? 0 : x,
            needY: y < 0 ? 0 : y,
        });
    }
    fnUp = () => {
        removeEvent(document, 'mousemove', this.fnMove);
        removeEvent(document, 'mouseup', this.fnUp);
    }
    render() {
        /*返回元素*/
        return (
            <div
                style={{
                    width: this.props.style.width,
                    height: this.props.style.height,
                    position: this.props.style.position,
                    left: this.state.needX,
                    top: this.state.needY
                }}
            >
                <div
                    onMouseDown={this.fnDown}
                    className={scss['drag-btn']}
                >
                    <span className={scss['btn-span']}></span>
                </div>
                {this.props.children}
            </div>
        )
    }
}
export default Drag